CHADS₂ Score Calculation
This patient has a CHADS₂ score of 5 points, placing him at very high risk for thromboembolic stroke with an annual stroke rate of approximately 12.5% without anticoagulation. 1, 2, 3
Score Breakdown
The CHADS₂ scoring system assigns points as follows for this 64-year-old man: 4, 1
C (Congestive Heart Failure): 1 point — The patient presents with dyspnea, shortness of breath, and oxygen saturation of 89%, indicating acute heart failure. 1, 2
H (Hypertension): 1 point — Blood pressure of 150/90 mmHg confirms hypertension (systolic ≥140 mmHg qualifies). 4, 1, 2
A (Age ≥75 years): 0 points — At 64 years old, the patient does not receive this point. The CHADS₂ system awards 1 point only for age ≥75 years; ages 65-74 do not qualify (this is a common pitfall—the newer CHA₂DS₂-VASc score includes age 65-74, but CHADS₂ does not). 1, 2
D (Diabetes Mellitus): 1 point — The patient is a known diabetic. 4, 1, 2
S₂ (Prior Stroke or TIA): 2 points — History of stroke carries doubled weight because previous thromboembolism is associated with highly elevated risk of recurrence. 4, 1, 3
Total CHADS₂ Score: 1 + 1 + 0 + 1 + 2 = 5 points 1, 2
Clinical Significance and Risk Stratification
A CHADS₂ score of 5 corresponds to a very high annual stroke risk of 12.5% (95% CI 8.2-17.5%) when no anticoagulation is used. 2, 3
The stroke rate increases by a factor of 1.5 for each 1-point increase in CHADS₂ score, demonstrating the exponential rise in thromboembolic risk. 3
Patients with CHADS₂ scores ≥2 require oral anticoagulation therapy with warfarin (target INR 2.0-3.0) or a direct oral anticoagulant unless contraindicated. 4, 2
Answer
The correct answer is D. 5
The patient's CHADS₂ score of 5 mandates immediate consideration for oral anticoagulation once hemodynamically stabilized, as the absolute benefit of anticoagulation substantially outweighs bleeding risk at this score level. 2